Galvanometer.



'PA'I ENTED MAR.;10,1908.

S. G. BROWN.

GALVANOMBTER. APPLICATION FILED APR. 7.100s.

. Fig.1.

ma netic lines of force. 30 be included in the c rcuit ofthls 0011, no reeanvanoungrnng no. ssns so.

Specification of Letters Patent.

Patented March 1c, 1908.

oriSim application film! n a 16, 1902, Serial No. 111,964.- Divided and this application filed. gni 1, 190a.

' 7 sax-mm. 151,491; a I

a To an whom it concern:

' ain, residin at 4 Great Winchester, in the 5 county of ondon, England, electrlcal en- 'neer, have invented certain new and useful provements Relating to Galvanometers, of which the-following 1s a ecification. This invention relates to improvements in galvanometers and has for its object to provide an efiicient means for-indicating whether a circuit in which it is included possesses self induction or capacity. v

This application is a CllVlSlOIl of that filed June 16, 1902, Serial Number 111,964.

A galvanometer cogtructedaccording' to this invention, is specially apphcable for use 'in'the manufacture of a cablegghlnejon tele-- graphic and'telephonic ui poses, the self inductance of whichis a apted to balance its capacity.

I *According to this 'm ntig fi pw galvanometer, whichl'term a reaction gal- 1 vanometer, comprises a wire coil delicatel suspended as 1n an ordinary DArsonval ga vanometer in the field of an electro-magnet excited by an alternating or fluctuating electric current so as to .normall 'cut some of the I plain resistance action will occur between the amperes flowing in the said coil and the alternatin mag- Inetic field;-the arrangement being suc that the amperes will be com letely out of phase 85 and in quadrature with t e alternating magnetism. If, however, capaclty or 1nduct1on be present in the circuit of the suspended coil, the amperes will be accelerated or retarded as the case may be, which will pro- 40 duce amovement of the: said coil in the one directionforcapacity and in the other direction', for induction. The movements of this coil-Fare 'preferablyindidated by a spot of light reflected upon a stationary scale by means of a small mirror carried by thsaid coil. Itwill be understood that the term alternati'ng or fluctuating electric current ap- "plies 'to-any'current which varies so as to induce'a voltage in the vcoil.

. By placing any apparatus, .say, a lengthof cable orlinei possessing self-induction in a degree to balance its ca acity, in the circuit of this suspended coil, t c said coil will indicate whether induction or capacity predomi- 5 5 nates in the cable or line.

nating electric current of given frequenc%dle- In order that the invention may be clearl understood and readily carried into eflectj will proceed to describe the same more vfiully with reference to the accompanying drawin s in which igure 1 is a view in plan of the reaction gmlvanometer Fig. 2 illustrates diagrammatically, the suspendedcoil, the mirror and F g- 3 i Y the scale ofthe said galvanometer. a diagram of curves illustrating the operatlonof the said galvanometer.

' 1 is an electro-magnet excited .by an alterrived from any conven ent source. cately suspended between the poles of said magnetis a coil 2 so placed as to be cut by mmmm 7 5 I some of the lines of force of the mg the said coil. The opposite si es of the coil 2 are connected by fine wires 3 3 Wl'th binding-screws 4, 4 to which are also connected ,field and'thereby to have volta e induced in.

the'ends of a length 5 of cable or artificial.

line, the self-inductance or ca acity of which it is desired to ascertain. .wire is intersected by capacity as denote ach leading-in 3,. If the self-induction balances the capacity in the cable 5, there will be no-move- 'ment of the coil 2 in the magnetic field, be-

cause there will be no reaction between the magnetic fieldand the amperes flowing in the coil 2; the latter being so arranged that the am eresset u therem will be exactly out of p ase with t e alternating ma etism.

If, however, ca acit or inductance e in excessm the cab e or me 5, then the am eres in the coil 2 will be advanced oi retarde and their reaction'on .the lines of force in the magnetic field cause the coil to swingin the one direction or thegother. Such movements of the coil 2 ma v be indicated by any convenient means, suc as a reflector 6 carried by the coil and adapted to throw a beam of li ht upon a scale 7, of which the sides are gra uated the one 8 for indicating capacity and the other, 9, for indicating induction. It is eas therefore, by studying the movements 0 the coil 2, to detect the presence of a preponderance of self-induction or of capacity in the said length 5 of cable or line and the value of such se f-induction or capacity may be readily ascertained by comparison between any convenient standard, and the 'larly, the se -induction only of a conductor deflection so roduced in the said coil. Simifor any given frequency or wave form of the alternating current of the magnet 1. Or the ca acity a one of the cable can be tested.

he action of the galvanometer illustrated in Fig. 3 in which I represents the alternating magnetic eifect from the magnet 1, A the electromotive force induced in the suspended coil 2, and B the ampere curve corres onding to the curve A. Normally, A and g) are, as shown, in quadraturewith regard to I and no torque is impressed on the coil 2. At this time the and shaded portions are e ual in area, and it is owing to their effects -alancing, that the coil remains unaffected. If, however, the cable 5 possesses a pre onderance either of induction-or capacity, t en the curve B will be displaced one Way or-the other and the area bounded by the right angle 1; a c and the curve line will either be greater or less than that inclosed by the right angle 0 e d and consequently a turning movement will be imparted in the one direction or the other to the coil 2. The inductance of the coil may be balanced by placing capacity in the leading in" wires.

'Although I have described above the application of the invention to the manufacture of a particular form of cable it will be readily 'eeneeo seen that the instrument may be advantageously applied to other uses where it is dcsired to indicate yariations in capacity or inductance.

What I claim and desire to secure by Letters Patent of the United States is z- A reaction galvanometer comprising an cately suspended coi ,said coil being mounted r to move rotatively in a horizontal plane, a reflecting mirror mounted on said delicately suspended coil, and capacity in said leadingin wires:

In testimony whereof I. have hereunto set my hand in presence of two subscribing witnesses this twenty third day of March 1903.

SIDNEY GEORGE BROWN.

Witnesses:

T. SELBYWARDLE, WALTER J. SKERTEN. 

